In starting a new unit, we have been building infrastructure, designing and conducting our experiments, and collecting preliminary data. First, to achieve mechanistic understanding of the functional connectivity among different cortical areas, we have started systematically examining the synaptic strength from different brain areas to diverse neuronal types in the primary somatosensory cortex, using electrophysiological methods combined with genetic tools. Second, to identify distinct microcircuits recruited by these different long-range inputs, we have been setting up imaging methods to monitor and manipulate activity of specific neuronal populations. Third, to understand the behavioral relevance of these circuits, we have been designing different types of behavior tasks that allow us to understand the role of these circuits in animals behaviors. The current hypothesis in our lab is that long-range projections from higher-order cortical and neuromodulatory areas recruit specific subtypes of GABAergic neurons in sensory cortex. As a key mediator, this distinct set of GABAergic neurons engage a specific local microcircuit.